1. Field of the Invention
The present invention relates to a method and apparatus for drilling through a target. In particular, but not exclusively, a bore is drilled through a target ensuring that waste material associated with the drilling process is directed in the direction of advancement of the drill.
2. Related Art
Many drilling techniques and apparatus are known in the prior art. Commonly a drive unit comprising a motor is used to rotate a drill bit at high speeds. The drill bit includes a cutting tip which cuts into a target as the drill is urged against the target. The drill bit may include rifling or other grooves which draw waste material, commonly known as swarf back out of the hole away from the cutting face where the front tip of the drill bit engages the target.
A number of problems are known with such drilling processes. One such problem is that when drilling through a target formed of a particularly hard material a great deal of heat is generated. Often a liquid coolant is used to lubricate the drilling process to prevent overheating. A problem with the use of liquid lubricant is that it can itself cause a hazard and can therefore require further steps to remove liquid.
Another problem with known drilling processes occurs when a target includes multiple materials each providing different physical properties when a bore is drilled through them. For example when drilling through a concrete wall which has pre-existing pipe work extending through it drilling out the metal pipe work and concrete can cause snagging. This is particularly true when drilling through large widths of wall for example through a number of meters in which case the force required to urge the drill bit through the wall can be prohibitive and/or snagging can make the process difficult.
It is also known that in certain hazardous areas drilling a hole through a wall to access that area has many peculiar problems associated with it. For example it is well known in the nuclear industry to have rooms, commonly known as cells in which radioactive waste is processed or generated. Under these circumstances the room is formed with thick walls and any breach of these walls could potentially cause an outward motion of radioactive or other hazardous material from the cell into an adjacent area. This should be avoided. Under these circumstances if a hole is to be drilled to provide access to the potentially dangerous zone care must be taken that waste material does not move from the cell to the adjacent region. In addition all potentially contaminated material including waste material from the drilling process and drill tips which have potentially come into contact with hazardous material must be collected within the dangerous zone for subsequent safe removal rather than being returned into a “safe” region where a drill is situated. Under these circumstances conventional drilling apparatus and methods do not provide a satisfactory system.
It is an aim of the present invention to at least partly mitigate the above-mentioned problems.